Continuous mining machine and control system therefor



Feb. 1, 1966 s. c. MOON l3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Original Filed Sept. 4. 1959 V16 Sheets-Sheet 1 Feb. 1, 1966 s. c. MOON 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Original Filed Sept. 4, 1959 16 Sheets-Sheet 2 INVENToR;

STERLING C. Moo BY Dsc-fassa,

S. C. MOON Feb. 1, 1966 CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Sheet 5 Original F'iled Sept. 4, 1959 JNVENToR; TEELI NG C. MOON J BY DECEH SED,

KATHAEYNE M. MOON,

S. C. MOON Feb. 1, 1966 CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Shee'cs-Shee'cI 4 Original Filed Sept. 4, 1959 INVENTOR; STEUNG C. MooNI KATHArew/NE M. MOON,

mlm H779.

Feb. 1, 1966 s. c. MOON 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Original Filed Sept. 4 1959 16 Sheets-Sheet 5 www, ,f k?. om r Mmmm@ mCEMw N NN IW. Y/ Em E AA S. C. MOON Feb. l, 1966 CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Sheet 6 Original Filed Sept. 4, 1959 INVENTOR; STERLING C. MOON, BY Dsc-fesso,

KATHARYNE MMOON, 5y mmm/W5rf'fwve/xI MGM/7 H775( S. C. MOON Feb. 1, 1966 CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Sheet 7 Original Filed Sept. 4, 1959 INVENTOR; TEELING CMooN,

DEcEAsa-D,

KATHAE'YNE M MOON,

M HTT'Y.

Feb. 1, 1966 s. c. MOON 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Original Filed Sept. 4, 1959 16 Sheets-Sheet 8 IN1/EN TOR,-

STEEUNG C. MooN, BY DECEHSED,

KATHAEYNE M. MOON, BY HDM/NISTRA'r/Evx M HTTY Feb. 1, 1966 s, C, MOON 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Original Filed Sept. 4, 1959 16 Sheets-Sheet 9 H EAD SEPARATE Feb. 1, 1966 Original Filed Sept. 4, 1959 s. c. MOON 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Sheet 10 UPPER RIGHT CUTTER ARM LOWER RIGHT CUTTER ARM Eig.

KATHAEYNE M. MOON, By HDM/N/sR/qT/e/ x S. C. MOO N Feb. 1, 1966 16 Sheets-Sheet l1 Original Filed Sept. 4 1959 lll" bmu www mwmm Div umm miv lu mM M @0L 0mm www.

. JNVENToR; STERLING CMOON) BY DECEHSED,

KATHAEYN E M. MOON,

HDM/N/STEHTE/x www Feb 1, 1965 s. c. MooN 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFORI Original Filed Sept. 4 1959 16 Sheets-Sheet l2 g j- I u) 1 O N m Q m2 L o U L0 W .m5 2K5" UEE c DIZ O L5 l v fm1: O o n 2252( D QE E I-UIZEJ T LD [kg t r ff) l] INVENTOR; STERUNG CMOON, BY DECEHSED,

KATHA E'YNE. M. MOON, 5y HDM/N/STEATE/ x,

Feb. 1, 1966 s. C. MooN 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Original Filed Sept. 4 1959 16 Sheets-Sheet 13 K INVENTOR l TEEUNG C. MOON,

BY DECEHSED,

KATHAEYNE M. MOON, 5y HDM/N/sv-E'nv-E/ x,

S. C. MOON Feb. 1, 1966 CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Shea?I 14 Original Filed Sept. 4 1959 nwf' S. C. MOON Feb. 1, 1966 CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Sheet 15 Original Filed Sept. 4 1959 KATHAEYNE NLMQON,

HTTY

s. c. MOON 3,232,668

CONTINUOUS MINING MACHINE AND CONTROL SYSTEM THEREFOR 16 Sheets-Sheet 16 Feb. 1, 1966 Original Filed Sept. 4 1959 v INVENTOR; STERLING C. MOON, BY DEcEqsED, KATHAEYN E M. Moo BY H WMM/g77 jg. 14l

United States Patent O 3,232,668 CONTINUUS MINING MACHINE AND CONTROL SYSTEM THEREFOR Sterling C. Moon, deceased, late of Dublin, Ohio, by

Katharyne M. Moon, administran-ix, Dublin, Ghio, assignor to Jeii'ey Galion Manufacturing Company, a corporation of Ohio Original application Sept. 4, 1959, Ser. No. 838,110.

Divided and this application Nov. 6, 1962, Ser.

- 12 claims. (ci. 299-1) This patent -application is a division of co-pending patent application, Serial No. 838,110, tiled September 4, 1959, for an Improvement in a Continuous Mining Machine and Control System Therefor.

The instant invention relates to continuous mining machines for the mining of coal, which are vadapted to be continuously advanced into the mine face to remove the coal therefrom, and which include conveying means to carry the mined material away from the mine face and to discharge the same at the rear of the machine, to permit the continuous advance of the mining machine into the face. More particularly the instant invention relates to a continuous mining machine in which there is provided a system for sensing the advance of the mining machine into the selected material in the mine face, which is the coal, with the sensing system providing signals indicating the advance of the mining machine into material other than the selected material, so that the course of advance of the mining machine may be guided in accordance with the signals to remove only the selected material from the mine face. The mining machine constructed in accordance with the instant invention further includes a control system for operating the mining machine from a position that is remotely located with respect to the mine face and the mining machine, the remote control system including the sensing system, and the mining machine being operated from the remote location in accordance with the signals which indicate the course of advance of the mining machine into the selected material.

It is'a prime object of this invention to provide a continuous mining machine provided with a control system for the operation of the mining machine from a position that is spaced with respect to the mine face and the mining machine.

It is a further object of this invention to provide a continuous mining machine for removing selected material from a mine face, provided with a system for sensing the course of advance of the mining machine into the selected material and providing signals for indicating the course of advance of the mining machine with respect to the selected material in the mine face.

It is another object of this invention to provide a continuous mining machine for removing selected material from a mine face, in which the mining machine is advanced into a determinate area of the mine face, and is provided with sensing means for sensing the material at the limits ofthe determinate area of the mine face, and providing signals indicating the advance of the mining machine into material other than the selected material.

lt is also an object of this invention to provide a continuous mining machine comprising a plurality of mining devices for removing material from -a mine face, in which the mining devices are arranged transversely across the front of the mining machine to remove material from an area Vof the mine face coextensive with the sweep of the mining devices, with the outermost mining devices including sensing means for sensing the material of the mine face at outer boundaries of the arear of the mine face from which selected material is removed, and including means to provide signals indicating the advance of the mining devices into material other than said selected material. Y

It is still a further object of the instant invention to provide a continuous mining machine comprising mining devices adapted to be advanced into a mine face for removing selected material therefrom, with the mining devices being arranged one above the other to remove material from a selected area of the mine face coextensive with the sweep of the mining devices, the latter including sensing means for sensing the limits of the mine face area from which the selected material is removed, and including means to provide signals indicating the advance of the mining devices into material other than the selected material in the mine face.

A still fruther object of the instant invention is to provide a continuous mining machine comprising two transversely extending rows of mining devices, with said rows being adjustable upwardly and downwardly relatively to each other, and adapted to be 4advanced into a mine fa for the removal of selected material therefrom, said mining devices dening a determinate area of the mine tace from which the selected material is removed, and the outermost mining devices of each row defining th-e limits of said determinate area, and said outermost mining devices including sensing means to sense the material at the limits of the determinate area of the mine face, and including means providing signals indicating the advance of the mining devices into material other than said selected material.

Itis also an object of the invention to provide a continuous mining machine comprising rotating mining devices adapted to be advanced into a mine face concurrently with the rotation thereof for removing material from the mine face, and said mining devices including means for indicating the rotary position of the mining devices.

Another object of the instant invention is to provide a continuous mining machine comprising rotating mining devices adapted to be advanced into a mine face for removing material therefrom, said mining devices being rotated in paths extending beyond the transverse perimeter of the mining machine to cut an area of the mine face of greater `dimension than the transverse dimension of the mining ma-chine, and being retractable within the perimeter of the mining machine, said mining devices including a signal system to indicate the position of the mining devices when they extend beyond the transverse perimeter of the mining machine.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings:

FIGS. 1A and 1B together are a side elevational View of a continuous mining machine embodying the instant invention;

FIGS. 2A and 2B together are a plan view of the continuous mining machine of FIGS. lA and 1B;

Y FIG. 3 lis an elevational view of the continuous mining machine showing the mining heads and the hydraulic mechanisms for adjusting the same; Y

FIG. 4 is a front elevational view of the mining heads of the mining machine showing the disposition of the mining devices;

FIG. 5 is :a sectional view of the lower mining head and a cutter arm `showing elements of the sensing system;

FIG. 6 shows the cutter arm or FIG. 5 partially in section;

FIG. 7 is a front elevational view partially in section of the cutter arm of FIG. 6;

FIG. 8 is a partial sectional view of the cutter arm taken on the line 8 8 in FIG. 7;

FIG. 9 is an enlarged view of the rear portion of the mining head shown in FIG. 5;

FG. l is a sectional view of the mining head showing elements of the sensing system and taken on the line lil--ll lin FiG. 9;

F-G. ll is a diagrammatic illustration of the hydraulic system for the mining machine of this invention;

FIGS. 12A to 12F together form a diagrammatic illustration of the electrical system for the continuous mining machine of this invention;

FIG. 13 is a plan View of the face of the control box embodying the electrical controls for the Continuous mining machine of this invention; and

FIG. i4 is a side elevational View of the top of the control box shown in FIG. l2.

The instant invention relates to continuous mining machines, particularly such as are adapted to be used in the mining of coal in underground operations, or in other mining operations in which the mining machine is adapted to be advanced `into the ground. Customarily the controls 'for such machines are placed at an operators station at the side of the machine, and the operator of the machine accompanies it as it advances into the mine face, it being understood that it is a characteristic mode of operation of such a continuous mining machine that it forms a room or tunnel in the mine .as it advances into the mine face, which room or tunnel is generally of greater dimension than the overall transverse dimensions of the machine, thereby providing room for the operator, and also providing room for backing the machine out of the room or tunnel and permitting it to bel maneuvered into position to advance into another mine face.

it is recognized that there are certain dangers inherent in coal mining operations. It is accordingly customary to follow prescribed procedures for insuring the safety of those engaged in the coal mining operation. The inherent dangers connected with the mining of coal are further reduced by the provision of apparatus for removing the coal from the mine face without requiring the proximate presence of a machine operator at the machine. in accordance with the instant invention there is provided a continuous mining machinev which is adapted for coal mining operations, and which includes a sensing system for sensing the material in the mine face and providing signals indicating the course of advance of the mining machine relative to the location of the coal in the mine face, so that the course of advance of the mining machine may be guided accordingly, to keep the mining machine in the coal seam. The continuous mining machine of this invention further includes a control system in which the sensing devices provide signals at a position remotely located with i.respect to the mining machine that indicate the advance of the mining machine, and controls at that remote position by which the mining mach-ine may be operated.

Referring to the drawings, FIGS. 1 4, there is illustrated therein a continuous mining machine 3f? embodying the instant invention, and comprising a main frame 31 supported on a pair of endless crawler traction treads 32, 33 disposed at opposite sides of the main frame 3l. The continuous mining machine Sil is propelled in forward or reverse directions by the crawler traction treads 32, 33, and may be steered by operating the crawler traction treads 32, 33 at different speeds. The crawler raction treads 32, 33 are operated by Aindividual hydraulic motors Se, 35, respectively, which are supported in the main frame 3l. An identical mechanical drive extends between each of the hydraulic motors 34, 35 and the respective crawler traction treads 32, for driving the latte. The drives to the crawler traction treads 3?., 3? each comprises -a pinion 36 driven by a hydraulic motor 34, 35 and driving a gear 37 which, in turn, drives a worm and worm wheel 38, the latter driving a pinion 3.@ which drives gear 4t? that is co-axially mounted on a shaft with a drive sprocket 4l that is engaged with a crawler traction tread 322, 33 to drive the latter. The operation of each of the hydraulic motors 34, may be reversed for driving the crawler traction treads 32, 33 in reverse, as when backing the continuous mining machine 3@ away from a mine face. Also, the rate of delivery ot' hydraulic fluid to each of the motors 34, 3S may be independently varied to drive the crawler traction treads 32, 33 at different speeds for steering the continuous mining machine 39.

At the forward end of the continuous mining machine El@ there is a forwardlyy extending support that is pivotally mounted on the main frame 3l on laterally extending pins 46. The support i5 extends forwardly from the main frame 3f. along the door 47 of the mine, with the support 45 being inclined downwardly in -a forward direction, as best seen in FIG. 3.

The support 45 carries a lower mining head 48 and an upper mining head e?, which are disposed in substantial v `cal alignment one above the other. The lower mining head ad is pivotally connected to the support 45 by laterally extending pins Sil. The upper mining head 49 is supported on the lower head ed and includes de pending guides 5l at the opposite sides thereof, which are engaged with traclrs 52 on the lower mining head t8 for guiding the movement of the upper mining head e9 upwardly and downwardly relatively to the lower mining head 48.

A double acting hydraulic cylinder and piston mechanism 55 is connected between the main frame 31 and the support 45 and is operative to raise and lower the support by swinging the same upwardly and downwardly on the pivot pins A double acting cylinder and piston mechanism Se is connected between the main frame l and the lower mining head 5.8, and by operation of the cylinder and piston mechanism 56 the lower mining head 4S, as well as the upper mining head t9 which is supported on the lower mining head 43, are tilted forwardly and rearwardly on the axis of the pivot pins Sil. A third cylinder and piston m chanism 57 is connected between the lower mining head 48 and the upper mining head 59, for raising `and lowering the latter relatively to the lower mining head 48.

The lower mining head t8 comprises a gear box 58 that extends laterally across the forward end of the continuous mining machine 3l). A plurality of transversely aligned shafts 59 extend forwardly from the gear box 58, there being live shafts 59 inthe disclosed embodiment of the invention. A radially extending cutter arm dil is secured to each shaft 59. Each cutter arm eil comprises integral bit holders 61, each of which is adapted to receive a plurality of forwardly extending bits 62. Within the gear box 5S there is enclosed a train of gears for rotating all the shafts 59V simultaneously, and in timed relation to each other. As seen in FIG. 4, the cutter arms o() have different circumferential positions. The two cutter arms 60 at the left side and the cutter arm 69 at the center of the mining head 48, as seen in FIG. 4, are rotated in a counterclockwise direction, while the two cutter arms 6th at the right side of the mining head 43 are rotated in a clockwise direction. The cutter arms 6u are each rotated at the same speed, and are disposed in different selected circumferential positions so that there is not interference of the cutter armsv 60 with each other during the simultaneous rotationy thereof.

The upper mining head 49 includes a gear box 63, which also encloses a gear train for rotating a plurality of transversely aligned shafts 64 that project forwardly from the front of the gear box 63. In the illustrated embodiment of the invention the upper mining head 49 is provided with ten shafts 64, each of which has secured thereto a radially extending cutter arm Each cutter arm 65 includes integral bit holders 66 for the reception of forwardly extending mining bits 67. The ve cutter arms 65 at the left side of the Lipper mining head 49, as viewed in FIG. 4, are rotated in a counterclockwise direction, and the live cutter arms 65 at the right side of the upper mining head 49 are rotated in a clockwise direc,-4

tion. All of the cutter arms 65 are rotated simultaneously at the same speed by the gears within the gear box 63, and are placed in different circumferential positions on the respective shafts 64, to avoid any interference between the cutter arms 65 during the simultaneous'rotations thereof.

As illustrated in FIG. 4, the upper mining head 49 is separated or raised with respect to the lower mining head 48, for mining a maximum height of material from the mine face. The cutters arms 60, 65 on the respective mining heads 48, 49 each operate in circular paths which are overlapping. The cutter arms 60, 65 are advanced into the mine face by the operation of the crawler traction treads 32, 33 advancing the whole mining machine 30 forwardly. As the mining bits 62, 67 are brought into the mine face, these bits operate to cut and break the material out of the mine face. The circular paths of the cutter arms 6i), 65 cumulatively define a mine face area from which material is removed in the mining operation. As seen in FIGS. 2 and 4, the laterally outermost cutter arms 60a, tlb, 65a, 65h at each side of the mining machine 30, extend laterally beyond the'mam`n1um lateral dimension of the mining machine 30, whereby there is produced as result of the mining operation a room or tunnel which is wider than the mining machine 30. Each of the cutter arms 6i), 65 is an eccentric element extending to only one side of its shaft 59, 64, respectively, whereby upon rotation of the cutter arms 60, 65, the laterally outermost cutter arms 66a, 60b, 65a, l65h may be withdrawn from the sides of the tunnel or mine room, and disposed in positions lying within the transverse dimensions of the mining machine 30. The cutter arms 60a, 60b, 65a, 65b thus being moved to positions out of contact with `the side walls of the mine room or tunnel, it is possible to freely maneuver the mining machine 30.

The forward end of the support 45 includes a ,transversely extending blade 7 0 which is adapted to be disposed on the floor 47 of the mine -behind the lower cutter arms 60. Since the cutter arms 60 operate in circular paths, they form cusps of material in the mine oor 47, and the blade '78 operating behind the cutter arm v60 removes these cusps from the floor 47, leaving the latter relatively smooth and level for the advance of the crawler traction treads 32, 33 thereover.

The forward end of the main frame 31 supportsra pair of electric motors 71, 72 for driving the lower mining head 48 and the upper mining head 49, respectively. The drive from the motors 71, 72 is delivered to a gear case '73 which combines the power of the motors 71, 72; A universal jointed drive shaft 74 extends from the gear case 73 to the lower mining head 4S, and a second universal jointed drive shaft 75 extends from the gear case '73 to the upper mining head 49. The drive shafts 74, 75 each include telescoping sections to permit adjustment of the mining heads 48, 49, as previously described.

The support 45 also carries one end of an endless chain conveyor 78, which is guided around an idler sprocket assembly 79 at the forward end of the support 46. The conveyor 78 extends rearwardly from the forwardend of the support 45, through the mine frame 31 of the mining machine 3i), as best seen in FIG. 1, and terminates at the rear end of the mining machine 30, at which point the conveyor.78 discharges the mined material. The conveyor 78 comprises two individual chain conveyors arranged side by side and each including oppositely disposed endless drive chains 80, tothe links of which there are secured a plurality of transversely extending flights 81, which are adapted to sweep the mined material over the bed 82 of the conveyor 78. The endless chain conveyor 78 is driven by a hydraulic motor S3 driving gears 84 which, in turn, drive a dual sprocket 85 that is connected by a chain drive 86 to dual sprockets 87, which are coaxially mounted on the driven shaft 88 with chain driving sprockets 89 that are engaged with the chains 80 for driving the latter.

The rotati f the cutter arms 65 of the upper' mining head 49 is in such directions as to sweep the vmined material towards the center of the mining machine 30.

Similarly, the direction of rotation of the two outer cutter arms 60 at each side of the lower mining head 48 is in such directions as to sweep t-he mined material in towards the center of -the mining machine 30. As the cutter arms 68, 65 are advanced into the mine face, the blade 7@ works along the mine door to remove the cusps left between the cutter arms 60, and also works its way into the material mined by the cutter arms 60, 65 to guide this material upwardly onto the support 45 to be received by the coveyor 78 and to be carried rearwardly thereby to the -rear end of the mining machine 30 for discharge of the mined material therefrom. Since the mined material is carried away from the area of the mine face as it is mined, the advance of the cutter arm 66, 65 is not impeded and the mining operation may be carried on continuously. At each side of the lower mining head 48 there is provided a pivoted gathering guide 90, which also works to crowd the mined material in towards the center of the mining machine Sil, to be received by the yconveyor 78 for carrying this material away from the mine face.

It is a characteristic of coal that it is found in the ground in seams which lie in relatively level planes. The coal may vary in thickness within ay given seam, and the same may rise and descend within the ground. Therefore it is customary for the operator of a continuous mining machine to view the face of the mine in which the mining machine is working to thereby visually determinewhether the mining machine is following the coal seam.. The mining heads 48, 49 are adjustable in a vertical direction relatively to each other for the purpose of adjusting to varying heights of coal in the coal seam. Thus where the coal seam is found to increase or decrease in height, the upper mining head 49 is elevated or lowered by means of -the heads separating cylinder and piston ymechanism 57, so that the vertical reach of the the coal seam is found to drift upwardly or downwardly, the mining heads 48, 49 can be tilted either forwardly to operate the mining machine in a descending path, or the mining heads 48, 49 can be tilted backwardly to follow the coal seam in an ascending path, the tilting of the mining heads 48, 49 being accomplished by use of the tilting cylinder and piston mechanism 56. As a further adjustment in the following the ascending or descending pat-h of the coal seam, the support 45 and the mining heads 48, 49 carried thereby, can be raised by means of the raised cylinder and piston mechanism 55.

Above and below the coal seam there is generally found material which is relatively harder than the coal, such as rock or shale. Ideally, it is desired that the cutter arms 60, not enter the relatively harder material which is found above and below the coal seam, for the reason that this material is waste as far as the coal mining operation is concerned, and any such material removed from the mine face with the coal must later be separated from the coal product. Also the operation of t-he cutter arms 60, 65 in material that is relatively harder than coal produces excessive wear on the mining bits 62, 67,'thereby severely reducing the life thereof, and making necessary more frequent replacement of the bits, which of course interrupts the mining operation and is therefore undesirable.

With the continuous mining machine 30 embodying the instant invention it is intended to make unnecessary visual observation of the mine face, and for this purpose the cutter arms 60, 65 include sensing means for the purpose of sensing the cou-rse of advance of the mining machine, and more particularly the advance of the mining bits 62, 67 of the cutter arms 60, 65, respectively, into material thatis relatively harder than the coal. The sensing means is included in a signaling system so constructed that it provides signals at a location remote from the mine face indicating the advance of the mining machine into material that is relatively harder than the coal. These signals are provided continuously during the operation of the cutter arms di?, 65 at a remotely located station at which all the controls for the mining tachine are located, as will be described in greater detail hereinafter, thereby making it unnecessary `for the machine operator to take a position immediately adjacent the mining machine when the signals provided by the signaling system indicate that the mining machine is advancing into amterial relatively harder than coal, the mining heads 48, 49 are adjusted as previously described to move the mining bits 62, 67 back into the coal seam, such adjustment being made in accordance with the signals of the signaling system. Similarly, the limits of the coal seam may be located by adjustment of the mining heads 48, d?. During such exploratory adjustment the signaling system Jill in icate the entry of the mining bits 62, 67 into material other than coal, whereupon the mining heads 4S, 49 may be adjusted back to just clear the material other than coal, and the mining operation will proceed with only the removal of coal from the mine face.

As seen in FIG. 4, the cutter arms 69, 65 remove material from ay determinate area 91 of the mine face, which is dened by the cumulative rotary sweep of the several cutter arms titl, 65 in the lower and upper rows of cutter arms respectively. The limits of the determinate area 91 of the mine face from which the material is removed are deined by the two outermost lower cutter arms oda, 60h of the lower mining head 48, and by the two outermost cutter arms 65a, ob of the upper mining head 49. Considering that the coal is found in laterally extending seams which are of a fairly regular nature, it is sufficient in sensing the location of the coal seam to perform this sensing function at the limits of the determinate mine face area 91- from which coal is removed by the cutter arm 6d, 65. Accordingly, the sensing devices are incorporated in each of the cutter arms, 66a, otlb, 65a, 65h. Since it is merely, necessary tofsense the material of the mine face at the limits of the determinate area @l of the mine face from which the coal is removed, the sensing` devices in the cutter arms oda, tiilb, 65a, b each operates in Iaquadrant which is co-extensive with a corner of the determinate mine face area 91 defined by the cumulative sweep of lall the cutter arms oil, 65'.

In the operation` of the continuous mining machine 3i) embodying the sensing devices in the several cutter arms, if the cutter arm 65a senses material other than coal in the mine roof, the upper cutter head 49 can be lowered relatively tothe lower cutting head i8 to thereby get below the relatively harder material, so that the mining machine in its continued operation will be operating solely in coal. Upon continued operation of the mining machine it may be found that the disposition of the relatively harder material in the roof of the mine indicates that the coal seam is drifting downwardly, which will call for a forward tilting of the mining heads 4S, e9. to operate the mining machine in a descending path. Depending on the location of the coal seam as determined by the several sensingdevices, it may be found that a further adjustment is needed to lower the support i5 and the blade 7l) to follow the downward drift of the coal seam for the purpose of removing the maximum height of coal from the mine face.

During operation of the mining machine 3), Where the sensing devices in either the cutter arms 60a, titl!) or the cutter arms 65a, 6517 do not provide any signals indicating the presence of material harder than the coal below or above the coal seam, the -rnining heads 4S, 49 and the blade 79 may be adjusted upwardly andr downwardly until there are produced signals indicating the location of the relatively harder material, following which the mining heads 48, 49 and the blade 7d may be further adjusted to clear the relatively harder material, and to remove the maximum height of coal from the mine face. Since the signaling system continuously provides signals to the operator at the control station for the mining machine, it is a relatively simple matter for him to make adjustments of the mining mechanisms of the machine as described hereinabove, directed to the purpose of removing the maximum amount of coal from the mine face.

Referring to FIGS. 5 to l0, there is illustrated therein the cutter arm 66a embodying the sensing device for sensing the material of the mine face, and for producing a signal at a remote station indicating the advance of the cutter arm 66a into material that is relatively harder than the coal. The cutter arm tlb is identical to the cutter arm dita. The upper cutter arms 65a, tb are shorter than the cutter arms titia, @db and only include a single bit holder. However, the sensing device embodied in each of the cutter arms 65a, 5b is similar in all respects to the sensing device embodied in each of the cutter arms ethz, only.

rhe cutter arm dita, as best seen in FGS. 5 and 7, in cludes an integral bit holder 6l located approximately midway along the length of the arm and `a separable bit holder 92 at the outer end of the cutter arm tica. The bit holder 92 is formed with a laterally extending shaft 13 which is received in a radially extending socket 4- inthe cutter arm 6tlg. The shaft 93 is supported in the socket @il by sleeve bear-ings 95, to permit oscillation of the shaft 93 and the bit holder 92 relatively to the cutter `arm Gtia. r.ihe bit holder 52 is disposed within the bifurcated end 96 of the cutter arm tiez, and works in the mine face in a couutercloclcwise direction, as viewed in FIG. 7. At one side of the bifurcated end @Si of the cutter arm dile there is seated a resilient backing member or stop 97 abutting the rear side of the bit holder 92. The backing member 97 is preferably made of relatively hard rubber, although other resilient devices may be utilized. The stiffness of the backing member' 97 is so gauged that it will resist and prevent movement of the bit holder g2 on the axis of the shaft 93 relatively to the cutter arm a, when the mining bits 62 are operating in coal. However, when the mining bits 62 are worked into material that is relatively harder than the coal, they meet with increased resistance applying a greater than normal force to the bit holder 92, overcoming the resistance of the backing member 97 and causing movement of the bit holder 92 relatively to the cutter arm Gtia, and resulting in oscillation of the shaft 93.

The end of the shaft 93 extends into a chamber 98 formed in the cutter arm doa. A lever arm 99 is keyed to the endy of the shaft 92 `and secured thereto by a nut lili). The lever army 99 extends radially from the shaft 93 into engagement with the actuator lt. of a switch 102 secured to a wall of the chamber $8, and which, in the embodiment of the invention described herein, is a micro-switch. When the mining bits 63 of the bit holder 92 are worked into material that is relatively harder than coal, there results a movement of the bit holder 92 relatively to the cutter arm 6in1, and a rotation of the shaft 93 and the lever arm E29, thereby operating the actuator itil and closing the switch its The switch to2. is connected in `an electrical. circuit, which is operated thereby, to` provide a signal at the operators remotely located station to indicate the advance of the mining machine 3i? and the mining rbits 62 into material that is relatively harder than the coal.

The cutter arm 69a. is mounted on the forwardly projectingy end of the shaft 59a. The shaft 59a extends through the gear box 5S of the lower mining head 48. The rear end of the shaft 59a is rotatably supported by a tapered roller bearing 105, and the shaft 59a is rotatably supported at the front of the gear box 58 by another tapered roller bearing ldd. Between the bearings 

4. IN A MINING MACHINE ADAPTED TO REMOVE SELECTED MATERIAL FROM A MINE FACE, MINING MEANS ADAPTED TO BE ADVANCED INTO THE MINE FACE FOR REMOVING SELECTED MATERIAL THEREFROM BY A ROTARY CUTTING AND BREAKING ACTION, MEANS FOR ROTATING SAID MINING MEANS, MEANS FOR ADVANCING SAID MINING MEANS INTO THE MINE FACE DURING ROTATION THEREOF, A SIGNALING SYSTEM FOR INDICATING THE ADVANCE OF SAID MINING MEANS INTO MATERIAL THAT IS OF DIFFERENT HARDNESS THAN SAID SELECTED MATERIAL, SAID SIGNALING SYSTEM INCLUDING ELEMENTS RELATED TO ROTATIONAL POSITIONS OF THE MINING MEANS, SAID MINING MEANS INCLUDING MEANS FOR OPERATING SAID SYSTEM IN RESPONSE TO THE ADVANCE OF SAID MINING MEANS INTO MATERIAL THAT IS OF DIFFERENT HARDNESS THAN SAID SELECTED MATERIAL TO PROVIDE A SIGNAL BY MEANS OF SAID ELEMENTS RELATED TO THE ROTATIONAL POSITION OF SAID MINING MEANS. 